It has become popular to use a Qi wireless charging application for a mobile phone, such as a smartphone, and the like, which can include an AC (alternating current) charging plate/base station that can be powered by a household power supply. The charging plate/base station can include a transmitter coil which can generate a magnetic field that can induce a voltage a receiver coil inside of a closed located smartphone, which can charge a battery in the smartphone. This magnetic resonance type charging technology is also described in for example, U.S. Published Patent Applications: 2017/0163070 to Lawrenson et al. and 2017/0338859 to Figgers, which are incorporated by reference in their entirety.
U.S. Pat. No. 9,421,920 to Jang, which is assigned to the same applicant as the subject application and is incorporated by reference, shows and describes a “mobile device accessory . . . ”, title, which can use a hinged metal ring accessory adhesively attached to the back of a mobile device, such as a smartphone. The '920 patent describes an adhesive that can permanently fix the metal ring accessory to the portable. The metal ring accessory can be used for grasping the mobile device in one hand, and can be used as a stand for supporting the mobile device upright on a surface, such as a desk and the like. The smartphone shown in the '920 patent can also use magnetic type resonance charging for charging the smartphone battery. However, the use of these metal rings can cause problems.
Magnetic resonance charging can cause fire or thermal burn due to overheating caused by foreign material (for example, metal pieces) between the transmitting coil (Tx) in the charging plate/base station and the receiving coil (Rx) inside of the smartphone. Since many of the ring shaped mobile accessories are made of metal and these metal objects between the transmitting coil (Tx) and the receiving coil (Rx) can cause thermal burn from the heated parts of FOD (foreign object detection) sensor which then stops the charger.
Thus, the need exists for solutions to the above problems with the prior art.